The shape of the radio wavefront of extensive air showers as measured with LOFAR

Corstanje, A.; Schellart, P.; Nelles, A.; Buitink, S.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Krause, M.; Rachen, J. P.; Scholten, Olaf; Veen, S. ter; Thoudam, Satyendra; Trinh, T. N. G.; Akker, M. van den; Alexov, A.; Anderson, J. M.; Avruch, I. M.; Bell, M. E.; Bentum, Mark J.; Bernardi, G.; Best, P. N.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Gasperin, F. de; Geus, E. de; Vos, M. de; Duscha, S.; Eislöffel, J.; Engels, D.; Fallows, R. A.; Ferrari, C.; Garrett, M. A.; Grießmeier, J.-M.; Gunst, A. W.; Hamaker, J. P.; Hoeft, M.; Horneffer, A.; Iacobelli, M.; Juette, E.; Karastergiou, A.; Köhler, Jana; Kondratiev, V. I.; Kuniyoshi, M.; Küper, G.; Maat, P.; Mann, G.; McFadden, R.; McKay-Bukowski, D.; Mevius, M.; Munk, H.; Norden, M. J.; Orrù, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H. J. A.; Scaife, Anna M. M.; Schwarz, Dominik J.; Smirnov, O.; Stewart, A.; Steinmetz, Matthias; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Toribio, C.; Vermeulen, R. C.; Vocks, C.; Weeren, R. J. van; Wijnholds, Stefan J.; Wucknitz, O.; Yatawatta, S.; Zarka, Philippe

doi:10.1016/j.astropartphys.2014.06.001

Cited by 66 publications

(70 citation statements)

References 21 publications

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“…In this analysis, we have used a plane wave approximation that has an angular resolution of ∼1°, which translates into an uncertainty of ∼2 g=cm 2 depending on zenith angle and shower depth. Using a more realistic reconstruction based on hyperbolic wavefront shapes, the accuracy increases to ∼0.1° [44].…”

Section: Uncertainty On X Maxmentioning

confidence: 99%

Method for high precision reconstruction of air showerXmaxusing two-dimensional radio intensity profiles

et al. 2014

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The mass composition of cosmic rays contains important clues about their origin. Accurate measurements are needed to resolve longstanding issues such as the transition from Galactic to extraGalactic origin and the nature of the cutoff observed at the highest energies. Composition can be studied by measuring the atmospheric depth of the shower maximum X max of air showers generated by high-energy cosmic rays hitting the Earth's atmosphere. We present a new method to reconstruct X max based on radio measurements. The radio emission mechanism of air showers is a complex process that creates an asymmetric intensity pattern on the ground. The shape of this pattern strongly depends on the longitudinal development of the shower. We reconstruct X max by fitting two-dimensional intensity profiles, simulated with CoREAS, to data from the Low Frequency Array (LOFAR) radio telescope. In the dense LOFAR core, air showers are detected by hundreds of antennas simultaneously. The simulations fit the data very well, indicating that the radiation mechanism is now well understood. The typical uncertainty on the reconstruction of X max for LOFAR showers is 17 g=cm 2 .

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Section: Uncertainty On X Maxmentioning

confidence: 99%

Method for high precision reconstruction of air showerXmaxusing two-dimensional radio intensity profiles

et al. 2014

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“…[22]). The LOFAR findings clearly indicate that a hyperboloid is the best way to describe the shape of the measured wave front [16]. A hyperboloid asymptotically reaches a conical shape at large distances from the shower axis and can be approximated as a sphere close to the shower axis.…”

Section: Pos(icrc2015)033mentioning

confidence: 79%

“…dio emission from air showers: the macroscopic models MGMR [11], EVA [16] calculating the emission of the bulk of electrons and positrons described as currents; the microscopic models ZHAires [17], CoREAS [18] based on full Monte-Carlo simulation codes; and SELFAS2 [19], a mix of macroscopic and microscopic approaches. All approaches agree in describing the radio emission [20].…”

Section: -3mentioning

confidence: 99%

Radio detection of Cosmic Rays with LOFAR

Hörandel¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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When high-energy cosmic rays (ionized atomic nuclei) impinge on the atmosphere of the Earth they interact with atomic nuclei and initiate cascades of secondary particles -the extensive air showers. Many of the secondary particles in the air showers are electrons and positrons. They cause radiation in the frequency range of tens of MHz. The LOFAR radio telescope detects this radiation in the frequency range 30 to 240 MHz. LOFAR has a high antenna density and good time resolution. In turn, the properties of the radio emission are measured in detail. The properties of the shower-inducing cosmic rays are derived from the air shower measurements, namely their direction, energy, and particle type (atomic mass). The uncertainties achieved are competative to established techniques. This demonstrates that the radio technique is now a standard tool to measure extensive air showers and to study the properties of the incoming cosmic rays. The mean logarithmic mass of cosmic rays as measured with LOFAR is derived as a function of energy. In an examplary study, these data are used to show that the radio measurements of air showers are now in a state to discriminate astrophysical models of the origin of cosmic rays. PoS(ICRC2015)033Radio Detection of Cosmic Rays with LOFAR J.R. Hörandel thus the amount of observing time in a given frequency band is not controlled by the cosmic ray project. In parallel to any observation the tile-beamformed data from all tiles are filled into ring buffers (Transient Buffer Boards), from which the last 5 s of data can be recorded when triggered. Triggers can be generated by inspecting the data with an on-board FPGA 1 or received through the LOFAR control software. In order to record cosmic-ray pulses, the dense core of LOFAR is equipped with an array of particle detectors [20], as also shown in Fig. 2. In routine observations, coincidences of several particle detectors trigger a read-out of the ring buffers [18].The HBAs can be sampled at two different clock frequencies, which allows for several different observing bands. The one mostly used in the present data-set is an event. During processing, the signals from all tiles in a station are first coherently beamformed in the cosmic-ray arrival direction as reconstructed from the particle data. When a significant signal, with a signal-to-noise ratio exceeding three in amplitude, is detected in the beamformed signal the station is selected for further processing and the event is selected as a cosmic ray candidate. Using a smaller search window, around the peak in the beamformed signal, a pulse search is then performed on the Hilbert envelope of the up-sampled signals from each tile. Up-sampling, by a factor 16, is needed such that the pulse maximum search is not the limiting factor in achieving the required time resolution. From the arrival times of those pulse maxima for which the signal-to-noise ratio in amplitude exceeds three, the direction of the cosmic ray is reconstructed. Additionally the amplitude (in each instrumental polarization) and...

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“…This project is collecting data and can detect the composition of the primary particle [20]. The first results have been published in several journals [21,22,23,24] and are also presented at this conference.…”

Section: Pos(icrc2015)684mentioning

confidence: 99%

NuMoon: Status of ultra high energy particle searches with LOFAR

Veen¹,

Buitink²,

Corstanje³

et al. 2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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The lunar Askaryan technique is one of the few ways to obtain a large enough collecting area to detect ultra high energy cosmic rays and neutrinos at the highest end of the known spectrum, above 10 21 eV. The flux of these particles is unknown, but if they are found they either point back to the best cosmic accelerators or they can be the products of the decay of exotic particles such as cosmic strings. Using the lunar Askaryan technique means searching for radio signals created by a particle shower that is induced when an ultra high energy particle collides with the Moon. The large collecting area that the Moon offers can especially be used at frequencies between 100-200 MHz, where the radiation is spread out over a wider angle and thus more of the lunar surface can be used for a possible detection. The NuMoon project therefore observes the Moon at these frequencies to search for nanosecond pulses. A first project with the Westerbork Synthesis Radio Telescope has placed the most stringent upper limits on the flux of ultra high energy cosmic rays and neutrinos. The next step is to observe with LOFAR, currently one of the most sensitive low frequency telescopes. In this contribution I will present the status and plans of the project.

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The shape of the radio wavefront of extensive air showers as measured with LOFAR

Cited by 66 publications

References 21 publications

Method for high precision reconstruction of air showerXmaxusing two-dimensional radio intensity profiles

Method for high precision reconstruction of air showerXmaxusing two-dimensional radio intensity profiles

Radio detection of Cosmic Rays with LOFAR

NuMoon: Status of ultra high energy particle searches with LOFAR

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